The efforts to save the 41 trapped labourers in the tunnel at Silkyara (Uttarakhand) have reached an advanced stage with the rescue team covering more than 45 metres of the around 65 metre blockage via augur drilling machine (horizontal drilling).
National Highways & Infrastructure Development Corporation (NHIDCL) resumed horizontal boring from the Silkyara end to rescue workers using an augur boring machine.
“Auger drilling started at 00:45 hours on Wednesday. A metallic object (Lattice girder rib) was encountered in the front of the pipe and the pipe could not be inserted further. Cutting of metallic object (Lattice Girder rib) using gas cutters was completed at 0230 hrs,” the Ministry of Road Transport & Highways (MoRTH) said in a media briefing on Thursday.
The drilling was again stopped for some time as a minor vibration was felt while laying and welding the ninth pipe.
Briefing the media on rescue efforts, National Disaster Management Authority (NDMA) Member Lt General Syed Ata Hasnain (Retd) said that authorities are working on half a dozen plans to rescue the trapped labourers.
The horizontal drilling using the augur machine is one of the best bets, he added.
When asked about the time it will take to reach the labourers, Hasnain said “Under ideal conditions, it should take around 12 hours to reach them. This is if no other blockages are experienced.”
Generally, it takes around an hour to drill 4-5 meters using the Augur machine and another hour to weld a 6 meter pipe to create the passage.
Hasnain said that all the medical facilities are in place and the teams are on standby to provide assistance to the labourers as and when they are rescued.
On November 12, a collapse occurred at the under-construction tunnel from Silkyara to Barkot, which led to 41 labourers getting trapped in the under construction tunnel.
Other rescue efforts
Hydro power generator SJVNL’s machine for the vertical rescue tunnel construction has arrived at the site and has been installed. The drilling is expected to start by Thursday evening.
Furthermore, THDC India has initiated the construction of a rescue tunnel from the Barkot end, with four blasts already completed, resulting in a 9.10 meter drift. Efforts are being made to carry out three blasts per day.
Some progress has also been made in the perpendicular horizontal drilling by Rail Vikas Nigam (RVNL). The equipment for micro tunnelling required for horizontal drilling has reached the site. Platform is likely to be completed by Friday and the equipment is expected to be set up by Saturday.
Another Augur drilling machine has been supplied by Larsen & Toubro (L&T), which has been kept on standby. Besides, the construction major has also provided the flexiprobe camera that was sent from Karnataka. It has been set up at site from November 20 evening for live visuals of the people stuck inside the tunnel.